CVE-2017-15705

Publication date 17 September 2018

Last updated 24 July 2024


Ubuntu priority

Cvss 3 Severity Score

5.3 · Medium

Score breakdown

A denial of service vulnerability was identified that exists in Apache SpamAssassin before 3.4.2. The vulnerability arises with certain unclosed tags in emails that cause markup to be handled incorrectly leading to scan timeouts. In Apache SpamAssassin, using HTML::Parser, we setup an object and hook into the begin and end tag event handlers In both cases, the "open" event is immediately followed by a "close" event - even if the tag *does not* close in the HTML being parsed. Because of this, we are missing the "text" event to deal with the object normally. This can cause carefully crafted emails that might take more scan time than expected leading to a Denial of Service. The issue is possibly a bug or design decision in HTML::Parser that specifically impacts the way Apache SpamAssassin uses the module with poorly formed html. The exploit has been seen in the wild but not believed to have been purposefully part of a Denial of Service attempt. We are concerned that there may be attempts to abuse the vulnerability in the future.

Status

Package Ubuntu Release Status
spamassassin 18.10 cosmic
Not affected
18.04 LTS bionic
Fixed 3.4.2-0ubuntu0.18.04.1
16.04 LTS xenial
Fixed 3.4.2-0ubuntu0.16.04.1
14.04 LTS trusty
Fixed 3.4.2-0ubuntu0.14.04.1

Severity score breakdown

Parameter Value
Base score 5.3 · Medium
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact None
Availability impact Low
Vector CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References

Related Ubuntu Security Notices (USN)

    • USN-3811-1
    • SpamAssassin vulnerabilities
    • 6 November 2018
    • USN-3811-2
    • SpamAssassin vulnerability
    • 13 November 2018

Other references